A flash flood warning is in effect for areas around and including New York City and Newark, New Jersey as a slow-moving thunderstorm continues to drop a relatively large amount of rain in a short period of time. 2-3 inches of rain have fallen near Newark in the past few hours.

As you can see, heavy rain has trained (continuously moved over the same area over and over again) over the region for well over an hour.

Here's the text of the warning from the National Weather Service:

BULLETIN - EAS ACTIVATION REQUESTED

FLASH FLOOD WARNING

NATIONAL WEATHER SERVICE NEW YORK NY

735 PM EDT FRI MAY 23 2014

THE NATIONAL WEATHER SERVICE IN UPTON NY HAS ISSUED A

* FLASH FLOOD WARNING FOR...

EASTERN PASSAIC COUNTY IN NORTHEAST NEW JERSEY...

NEW YORK (MANHATTAN) COUNTY IN SOUTHEAST NEW YORK...

SOUTHERN BERGEN COUNTY IN NORTHEAST NEW JERSEY...

EASTERN ESSEX COUNTY IN NORTHEAST NEW JERSEY...

HUDSON COUNTY IN NORTHEAST NEW JERSEY...

* UNTIL 1030 PM EDT...

* AT 733 PM EDT...THUNDERSTORMS WERE MOVING EAST AROUND 20 MPH AND ARE PRODUCING VERY HEAVY RAIN WITH RAINFALL RATES BETWEEN 1 AND 2 INCHES PER HOUR. THIS IS EXPECTED TO CAUSE FLASH FLOODING OVER THE WARNED AREA.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL CREEKS AND STREAMS...URBAN AREAS...HIGHWAYS...STREETS AND UNDERPASSES AS WELL AS OTHER DRAINAGE AREAS AND LOW LYING SPOTS. TO REPORT FLOODING...HAVE THE NEAREST LAW ENFORCEMENT AGENCY RELAY YOUR REPORT TO THE NATIONAL WEATHER SERVICE FORECAST OFFICE IN UPTON NY.

&&

As of 7:58PM EDT, 2 inches of rain have fallen in Newark, with three inches of rain just north of the city. These heavy rainfall rates will continue until the storms move away from the region or slowly start to collapse.

Here's the storm total rainfall for this storm, valid through 7:58PM EDT.

At 8:00PM EDT, the National Weather Service reported that there are "motorists stranded on Tonelle Avenue in Jersey City," and that the fire department is responding to perform water rescues.

Remember not to drive through any flooded roadways, as it's impossible for you to tell how deep the water is until it's too late. Almost half of all deaths that occur in flash flooding are a result of people driving into floodwaters. Not only does it put you at risk, but you're risking the lives of the people who'd have to come out to save your dumb ass, too.

If you have any cool pictures of the storm as it moved into the area, Tweet them to me @wxdam and I might include them in later updates to this post.

Update 8:25PM — More water rescues, this time in Newark, per NWS: "Numerous cars trapped on Route 21 near the viaduct. Fire department responding"

Thanks to "mynameisjohn" on Twitter for sending this pic of the storm as the heavy rain swept over NYC.

Also, inbound flights to LaGuardia are on a ground stop until at least 9:00PM EDT, with airborne aircraft seeing almost a one hour delay. Flights scheduled to depart to JFK Airport are being held in a ground stop until 9:30PM EDT. Newark Airport is seeing arrival and departure delays of almost two hours.